Our project's classrooms are all less than 20k cu.ft. and have "clouds" of acoustical ceiling tile (approx. 60% ceiling area) and either drywall soffit (approx 5%) or areas open to structural bar joists, metal deck, ductwork, etc. to be painted out white (approx. 35%). Realistically, the ACT clouds work better than a continuous ceiling because bot sides are providing sound absorption (I would think). We also will have carpet in most classrooms. With the large areas of glazing for daylight on one wall, marker and tack boards on another, and millwork covering a third, we could cover the remaining wall from floor to ceiling (not a realistic idea) with acoustical material and still not quite meet the requirement. Is our only option to perform the calculations under "CASE 2" as would be required for larger classroom spaces? Would this be acceptable to the GBCI reviewers? I don't see anywhere where they state you have your choice of CASE 1 OR 2. I really don't want to try to do the calculations, but since it is a prereq and not an option, do I have any other choices??
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Daniel Hicks
Daniel Hicks, E.I., INCEGeiler & Associates
267 thumbs up
December 14, 2010 - 11:43 am
Hi Tim:
Once you get into the actual EQp3 template, you will find three options available:
-Complete an NRC Table to show that room materials with NRC 0.7 or higher are equal to or greater than the ceiling area.
-Perform reverb time calculations based on ANSI S12.60-2002
-Perform reberb time measurements after the room is built based on ANSI S12-60.2002
It doesn't sound like the first option is available for you, so you'll have to either make RT calculations or measurements to satisfy the prereq.
I don't know why all three of these items aren't listed in the LEED documentation but they are found in the template (at least it has been in the most recent projects I have worked on). Another caveat found on the template but not in the documentation reads "NOTE: if the core learning space is: a) not rectilinear, b) has a sloped or non-flat ceiling, or c) has a ceiling height that is 12 feet or more above the finish floor, then only the latter two options are available (ANSI Calculations or Measurements)."
Hope this helps,
Daniel
Tim Hoeft
AIA, LEED APStraughn Trout Architects, LLC
94 thumbs up
May 11, 2011 - 12:10 pm
Daniel,
Thank you for your help on my question and all of the other questions you have helped on this Prereq/Credit.
Since my initial question, "value engineering" has eliminated our ceiling clouds. We can now achieve the requirements for reverberation time with a combination of suspended acoustical tile ceiling and some tackable acoustical panels to make up the difference for a small drywall soffit area.
Looking at the LEED Online Form for IEQp3, we must also address background noise with either (Path 1) a summary report of calculations based on ASHRAE chapter 47 [Upload L-15], or (Path 2) an acoustical design methodologies description to ensure compliance with ANSI S12.60 for background noise [Upload L-16].
To me, it appears that it would be easier to write a descriptive narrative of the space [L-16] than to perform calculations (No acoustical engineer on this project). Do you know where I can find an example? Am I correct to interpret that there are no required calculations for [l-16]?
The documentation toolkit on this website provides an example from your office (thank you!), but it clearly notes that it is not approved for LEED 2009.
Our mechanical engineering consultants are willing to help, but they continue to remind us that they are not acoustical engineers.
Any suggestions, directions, or examples would be very helpful. Thanks!
Daniel Hicks
Daniel Hicks, E.I., INCEGeiler & Associates
267 thumbs up
May 25, 2011 - 4:36 pm
I’ve never done the second approach. I've always made the calculations and then provided recommendations to the project team to get the noise levels down to where they were needed.
In any case, a good place to start would be to get a hold of ANSI S-12.60 and follow it’s recommendations where you can, and then write a narrative stating what exactly you did…basically restating the recommendations you incorporated from ANSI in your own words. It doesn’t appear that any calculations are required, just that you follow the recommendations in the ANSI document and then just state what you incorporated into the design.
Hope this helps.
Dana Murdoch
144 thumbs up
July 26, 2011 - 6:07 pm
Where does it state that classrooms with sloped ceilings must use the latter two options (ANSI Calculations or Measurements) instead of using the Option 1 - Minimum NRC?
Also, when calculating materials within the room, some of the language within the credit states "specify ceiling and wall finish materials" and other language on this website states "ceiling, wall and floor material." Our classrooms will have carpet - can flooring material be used in the NRC calculations?
Thanks!